Buoy



FIG. 1 is a perspective front, top, and left end view of a buoy, showing my new design;

FIG. 2 is a left end view thereof, the right end view is a same image;

FIG. 3 is a front view thereof, the rear view is a same image;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof. 

The ornamental design for a buoy, as shown and described. 